Gas anaesthetizer



Dec, 12, 1933. o. H. PEAK GAS ANESTHETIZEH 3 Sheets-Sheet 1 Filed March 19. 1930 lllll|mm hvemor O.//. Peak Dec. 12, 1933. o. H. PEAK GAS ANJESTHETIZER 3 Sheets-Sheet 2 Filed March 19, 1930 9 6 0 a Q 2 6 7 n 4 n. w w m /2 9 2 3 3 I41 M4 5 a 8 9 8 8 6 2 2 PM 8 3 6 M 9 9 H I I Vl/l/l I V0 for O. H. Peak 6, vi/MAJ A ffm-neys Dec. 12, 1933. o. H. PEAK GAS ANIESTHETIZER 1930 3 Sheets-Sheet 5 Filed March 19 Patented Dec. 12, 1933 s s v UNITED STATES PATENT OFFICE GAS ANZESTHETIZER Orin Harry Peak, Hollywood, Calif; 7 Application March 19, 1930. Serial No. 437,068

.6 claims. (o1. zs-aoa) This invention relates to anaesthetizing'appation, to personally control the administration of ratus. the anaesthetic, and with such case and surety An object of the invention is to provide imthat his intention need not be unduly distracted provements in existing apparatus of this general from the progress of the operation itself.

class, whereby the safety, surety, facility, and A further object is to so arrange the control 60 effectiveness of the administration of anaesthetics, valve and the parts associated therewith, that are materially enhanced. the operator is enabled not only to enrich or A more detailed object is the provision of a weaken the gas being supplied to the patient, but relatively simple and easily operable mechanism also to supply either the nutrient gas or the 10 whereby a. gaseous anaesthetic such as nitrous anaesthetizing gas in pure, concentrated form, 'oxide, and a nutrient gas such as oxygen or air, and without destroying the setting of the valves or a mixture thereof, may be administered to a. maintaining a normal mixture of the gases. patient in known quantities, and at proper pres- Thus, when the emergency requiring the adminsure corresponding to lung capacity and pressure, istration of either gas in more concentrated form respectively. Such apparatus is used to mainthan normally, is past, the normal mixture may 70 tain a patient in a state of full anaesthesia or in again be instantly supplied. a state of analgesia, i. e., a state of unconscious- The invention poss other bj s and a ness sufliciently profound to render the patient vantageous features, some of which, with those insensible to pain, but not so deep that difiiculty enumerated, will be set forth in the following deis apt to be encountered in resuscitating the scription of the inventions particular embodipatient whenever desired. ment which is illustrated in the drawings 'accom- A further object is to effect improvements in panying and forming apart of the specification. known apparatus used for this purpose, of such Referring to the drawings: a nature that the anasthetist may readily effect Figure 1 is a front elevation of "a piece of 25. variation in the quantity of either of the gases anasthetizing apparatus incorporating the prinadministered, so as to quickly compensate for any ciples of the present invention. unexpected development tending to affect the I Fig. 2 is a horizontal, compound sectional view, depth of the patients anesthesia, and to counthe planes of section being indicated by the lines teract either too great or too little '2. content of 2-2 of Fig. 1, and the direction of view by the either of the gases in the mixture supplied to the arrows. i 3 patient. v Fig. '3 is a transverse, vertical sectional view Another object is to provide a resiliently distaken upon the line 3-3 of Fig. 1, with the direc-' tensible reservoir which may be filled with a mix tion of view as indicated. ture of the gases in proper quantitative relation-' Fig. 4 is an enlarged, detail sectional view taken ship, and a similar reservoir for the reception of upon the line 4-4 of Fig. 1, withthe direction of a quantity of each of the gases in an undiluted view as indicated. 1 condition, each of the reservoirs being of such Fig. 5 is a diagrammatic view showing the condesign that its inherent tendency to collapse, nections between the various elements of my imimposes the proper pressure upon the gas so as to proved apparatus. 40 insure delivery thereof, to the patient. In terms of broad inclusion, the apparatus of A still further'object' is to provide valve means the present invention comprises a source ofsupwhereby the delivery tube which communicates p y 0f ach Of a plurality of fluids. a resiliently with the face "mask, and which hence conducts distensible reservoir associated with each, va dethe gases to the patient, may optionally and praclivery tube for conducting gas from the apparatus 45 tically instantaneously be connected to any one to a patient, and valve means whereby communi of the three reservoirs, and at the same time seal cation may be established optionally between the both of the other two reservoirs, so that the gases patient andany or all of the sources of supply. therein are held available for instant use and The valve means is also adapted to automatically at proper pressure to be drawn upon whenever establish communication betweenasource of sup so desired. j 1 ply and the reservoir associated therewith When- Yet another Object in this Connection, s o so. ever that source of supply is connected to the supp y the apparatus and especially t econtrol ply tube, and also with another reservoir convalve therefor, that no especial Skill is necessary taining a, mixture of the gases, according to preits p p r manipulation, thus pe it ing a determined proportion, when the supply tube is surgeon or other person conducting an operaconnected to both sources of supply.

Specifically describing the invention in its preferred embodiment, the apparatus is preferably supported upon a suitable, portable stand 11 have ing a base 12, whereby the apparatus may be disposed in any convenient location. The apparatus itself, comprises a centrally located valve housing 13 having a sleeve 14 extending downwards from the bottom thereof, and adapted to be received upon the upper end of the stand 11, to suitably position the device. Arms 16 and 17 extend from opposite sides of the housing 13, to support pressure reducing valves 18' and 19 respectively, of well-known design.

18, 19, each of these brackets 21 being adapted to establish communication between the asso elated reducing valve, and a steel cylinder 22 of the type commonly employed for storage and transportation of gases under high compression. The cylinders 23 connected to the reducing valve 19, should contain a, gaseous anesthetic such as nitrous oxide,'carbonic acid gas, ethylene, or other similar agents, whereas the cylinders 22 associated with the reducing valve 18, should contain a suitable nutrient gas such as oxygen or air.

The purpose of employing a plurality of cylinders 22, 23, communicating with each ofthe reducing valves 18, 19, respectively, is to prevent the possibility of completely exhausting the available supply of either gas during the progress of an operation. a 1

Inasmuch as the design'of the reducing valves 18, 19, has no bearing upon the present invention, their construction need not be described herein. Sufilce itfor the purpose of the present disclosure therefore, to explain that both cylinders 22, 23, associated with each reducing valve 18, 19 respectively, are adapted to supply gasthereto at relatively high pressure, and that the reducing valve 18 is provided with preferably a pair of ou lets 24and the other valve- 19 having a single outlet 25-each,reducing valve being susceptible of adjustment so as to deliver gas at a known re.- duced pressure by way of each outlet 24.

One of the outlets '24 of the reducing valve 18 communicates through a suitable length of tubing 26 with a needle valve 27 which is mountedupon the arm 16; and from the needle valve 27 a length of tubing28 communicates with one side of the valve housing or chamber 18. Similarly, the outlet 25 of thereducing valve19, communicates through a tube 29 with'a needle valve 31, and from the needle valve 31 a length of tubing 32 leads to the valve housing 13 at a point closely adjacent that at which the tubing 28 enters thereinto. e

A valve- 36 is mountedfor. rotational movement within the valve chamber 13, th engaging faces of the valve 36 and chamber 13 preferably being conical as clearlyshownupon Fig. 3, for the purpose of establishing a more efficient joint therebetween. 4 The valve 36 is hollow, and is open at the bottom thereof so that the bore 370i the valve 36 is'at all times in communication with a relatively large opening 38 inthe bottom of the chamber 13. A nipple 39 communicates with the opening 38, .and is adapted to have mounted thereon a delivery tube 41 which is flexible and which leads to a conventional face mask (not shown) adapted to be engaged upon the face 'of a patient so as to cause him to breathe gases delivered to him throughthe delivery tube 41.

The tapering walls 42 of the valve 36, are provided with diametrically opposed openings or ports 43, each of which is relatively large, so as Preferably a pair of brackets 21 are associated with each of the reducing valves tween the bore 37 of the valve 36 and both tubes 28 and 32 through one of these ports. Hence, when the valve 36 is positioned to bring one of the ports 43 into registration with the entrance of both tubes 28 and 32 into the chamber 13, both oxygen and N20 may be delivered to the patient through the delivery tube 41.

Diametrically opposite the area at which the tubes 28 and 32 enter the chamber 13, another opening or port 46 is formed in the wall of the chamber 13. From this opening 46 a relatively large tube 47 extends, the outer end 48 of the tube 47 extending downwards and being adapted .to receive the neck of a resiliently distensible reservoir 49'. This reservoir 49 is preferably in the form of a rubber bag of capacity materially exceeding maximum lung capacity, so thatthe reservoir 49 is capable of holding in store, a quantity of gas sufficient to supply a patient when taking the deepest possible breath. The inherent tendency of thereservoir 49 to collapse, which is caused by the elasticity of the material of which it is composed, results, in. imposing a sufficient amount of pressure upon the gas contained therein, to supply the'gas to the patient at approximately lung pressure, i. e., about five pounds per square inch. above atmospheric.

Means are also provided for controlling the rate of flow of each of the two gases, so as to keep the reservoir 49 supplied at a rate sufficient to compensate for the rate at which the patient withdraws the'mixture of gases from the reservoir 49 during normal respiration. (In the case of an adult person, this rate is approximately 1.5 liters per minute). Each of the. tubes 28 and 32 enters the valve chamber 13 through an L- fitting 51 to'which the associated tube 28 or 32 is coupled through the expedient of a union 52 of conventional design. The structure of this union is best shown upon Fig. 4, and includesa ferrule 53 threaded onto the outer end of the associated L-fitting 51. The end of the associated tube 28 or 32, as the case might be, extends through asuitable aperture 54 in the outer end ofthe ferrule 53, and seats within the end of the bore 56 of the L-fitting 51. However, a slight bead 57, is formed on the end of the tube'28 or 32, as the case might be, this bead 57 seating within a counterbored portion 58 of the bore 56. The bead 57 is of greater diameter than the hole 54 in the ferrule'53, through which the tube extends, with the result that when the ferrule 53 is tightened, the head 57 is crowded tightly into the counterbored portion 58 of thebore 56, to establish an efficiently tight joint between the L- fltting 51 and the tube 28 or 32. This is the construction of a well-known type of union whereby tubing such as the well-known copper tubing may be joined to any desired type of fitting. However, the presence of such a joint in each of the tubes 28 and 32, facilitates the provision of a restriction in each tube, inasmuch as such restriction may easily be formed by filling the extreme end of the tube 28 or 32, as the case may be, with solder 59 or other suitable material,

and then drilling a hole 60 of known diameter, through the material disposed within the tube. By this means, restricted orifices 61 and 62 may easily be formed in the tubes-28 and 32 respectively, thus making it possible to control the flow mantra:

of gas through each tube :28Jandt 32; toraecuraselyr attain a predetermined Frate ibyamani puiatmgithea needle valves 27 and 31' respectivelyz Each ofthe tubes. 28: 8.1'ldf3 2:.isfprovidedwdtht as. pressure gauge 63, 64 respectively, between: the: associated needleavalve 27or. 3114152 thea-case mightbe, and theLaSSOciated orifice 6l'.lori'62,-.as l the case may be. As a: resultrof': thiaarrangee ment; each needle valver2'l; 3ILmay be-2-mamrnh lated so as to establisha 'predeterminedzpmssmec within the associated 'tubei'28, 32-e-these pressures: b'eingindicated upon thetgauges 63::and 64' resspectively, Therefore; knowingzthe pressure be hind reach 1 orifice 7' 61'; 621'. and the: cross-sectiomt'.

1 area." of each 1.orifice, the mew: tflovw mayieaailyi'" be calculated, and each of the needleevalvesi zfli and 31 :will be-so regulated that thefratemtifibw or both gases .into the valve'chamber: 13;: is; sum cient to keepithepatient:supplied with theproper amount of oxygen and: N20 to insure: his a being: maintained in that state of anaasthesiaudesiredt It" should be explained that' the: face? usually employed; is provided? with. exhaling valve whereby gases expelled from the patients; lungs, are. discharged: to :the atmosphere? instead of 'being forced backsinto: thevanaesthetizing iaps paratus, with the: result that'zthere: isi an inter mittent flow in but one direction, through :thesde-r liverytube 41: The .fact that the iresiliientlydise tensible'reservoir 49 is*in':comm1mioation.,withi;

the face mask; compensates for this intermittent; flow of 'thegasesfrom thei apparatus'rto'r thze pa v tient; as a result of his: respiration; Whenathec patient is 1 inhaling, .theimixtureof gasesrrwitlxbe; supplied to'him asaresultor .th'erpartiat of the reservoir 49; and:.'while;he2is exhalingzithea bag "49 will 'again be filledibythe 'Jfl OW'OI fttietgnsess through the tubes 28 and 32', into the rvalvemhanrsber 13. Consequently; a-imlxture'oi' the-".twmgasesa according. to predetermined quantitatiiei rela:-

tionship, is continually suppliedizumier suitable? pressure :to the face mask, so :that each tlme'rthe patient inhales, his lungs will be: supplied within this mixtureofgases.-

Attention; should be" directedstonthe facttthatr: the: outlet opening 33 v through a winchsignsz fiowsr into' the delivery ,tube- 41 ,i andraisof the opening 46? and tube" 47 through which communication: is established between "the :bag49iand1 theedelivery tube" 41, are of relatively'largercrossesectiozniz: area, making it'possible'fto' supply: animate:

quantityof gas to the patient-evendrrrthereventsof" an extremely rapid inhalatioiraswclnfora can ample, as when the patient gaspszz Y Althoughi manipulation-rot themeedle: valves-s27: and"31 :permits accurate reguiationzofi tl ievriemness of'the' mixture of gases supplied torth'ermw tient, so that just :the desired degree" ot ianmthe sia' may be" maintained 'to suittherpatient srz=res quirementsas determined'by the operator, it :free quently happens during the courseroi anwomm' tion that some event transpires which: requires: a prompt variation" in the'richness- :ofithecmix-' ture. Particularly true is this"; in? the case oft.

- oral operations whereit is 'necessary2twadminister the anaesthetic to the patientw through: the" expedient of a' maskcovering his? nose- When such a mask is used, a patient occasionally, inhales through his mouth, or the operatordisturbs'the mask, permitting the patient to inhale a larger amount-of oxygen-thanvhe: should.be;-. allowed to receive, to preserve=the desiredistate" of anaesthesia; Consequently, I: have; provided? means in my, improved anmsthetizi'ngti' appae gaseousanmsthetic' supplied to the-delivery tube 41; and inasmuch as it occasionally occursthat.

too amixturetof anaeaesthetic gas is supplied to Z-tIIEEDatiEBt, I'i haveialso' provided: means for instantly'supplyingrpure oxygen'to the delivery tubes4-1; so'astozenable'the operator'to effect parvalve-chamber-13*at apoint suitably spaced from:

the port 46ipreferably the angular displaceenters the chamber :13 and the port 46 through which communication is establishedwhen the reservoir 49 is 60.

The second resiliently distensible reservoir 69 connects through a relatively large tube 71 with the valve chamber 13, entering thereinto through a port '72 diametrically opposite'the port 68, so that when the valve36- is turned to bring its ports 43 into register'with both ports 68 and 72, such positioningof the valve '36 will permit N20 to flew-through the tube 66 into the valve'chamber13 at arate determined bythe cross-sectional areaxofthe orifice 6'7 and the pressure within the tube-66 '-asgoverned by the needle valve 31' and as indicated'upon the gauge 64. It should be observedhowever; that whenever the port 68 communicates with-the interior of the valve chamber 13, the port- '72 also communicates therewith so thatnitrous oxide is supplied to the patient through the'port 38in the bottom of the valve chamber 13; noto'nly from the tube'66, but also from the reservoir 69 which is ofthe same construction as-the reservoir 49. This makes it possible to sustain the same pressure upon the gases supplied to the patient, and to'permit continnedrespirationeven' though pure N20 is being supplied to the patient.

The means'for-supplyingpure oxygen to the patient, is in the form of another tube 76 leading directly from'anotherof the outlets 24 of the reducing valve 18, to a port '77 in the valve cham ber 13. Preferably this port 77 is disposed upon the oppositee side ofthe port 46 from the port 68, the port 46 being disposed midway between theports 68" and '77; The'tube '76 is similarly provided with'a restricted orifice 78.

Diametrically" opposite the port 77, a port 81 is'disposed, and'through this port 81 a third resiliently di'stensible reservoir 82 communicates with the valve chamber 13 by means of a relatively large'tube'83i' Thus it maybe seen that pure oxygen-may besupplied to the patient bythrowing the valve 36 in the direction opposite that which result'sin supplying thepatient with pure N20. In

other words; when a-situation arises during-theprogress of an operation, which requires that the-- rotate the'valve 36 so as to bring the ports 43 thereofjintdregister with the ports 77 and 81, whereupon communication will be established between thedelivery tube 4-1', the tube-'76, and also w the -reservoir82. Since. this reservoir 82 is of the same constructionas thereservoirs 49.- and 69,

the same pressuremay be maintained; within the entire'system, causingcontinuedfflow of "gas ratus, for instantly increasing; the; content or: tmtliepatientat the samerataalthoughthe-ap= paratus has been so adjusted as to supply pure oxygen to him.

It is to be observed that the tube 76, instead of.

leadingfrom the needle valve 27, leads directly from the pressure reducing valve 18. The reasonfor this is that occasion frequently arises requiring the prompt, partial resuscitation of .the pa-. tient, which may be accomplished by-supplying him with a relatively large quantity of pure oxygen. Under some circumstances. the quantity of' oxygen required, is considerably greater. than that which is used throughout the major portion of the operation, as one of the components .of themixture of gases. Hence, if the tube'76 led from the needle valve 27, it would be necessary to. change the adjustment of that valve in order to I supplythe necessary quantity of oxygen'to tha patient, to meetsuch an emergency. However,

with the tube 76 arranged as hereinabove de scribed, and by making the restricted orifice 78' cover plate 86 which is rigidly secured across the top of the valvcchamber 38 by meansof aplurality of screws 87 or their equivalent. The valve 36 carries a stem 88 which is rigid therewith-and which extends rotatably through the plate 86, an I operating handle 89 being rigidly secured to the stem 88 above the plate 86. spring 91 is interposed between the plate 86- and the top 92 of the valve 36, this spring. serving to continually press the valve 36 downwards. so as a to establish a tight seal between it and the taper ing walls of the valve chamber 13. a w

Preferably three bosses 93 are formed upon-the upper face of the plate 86. A pointer 94 registers with the central one of these bosses 93 when the. ports 43 of the valve are in register with theports 46, and with the entrances of the tubes 28 and 32 into the valve chamber. The other twoof these bosses 93 are adapted to be engaged by'sorne portion of the handle 89, and limit movement thereof,

beyond those positions in which pure oxygen-and; in the patients condition is so slight that only a pure nitrous oxide are supplied to the valve. cha n ber..

' Operation The anzesthetistfirst determines .the richness of 'the anaesthetic gas which is to be suppliedto the patient, and then sets theneedle 'valves 27 and 31 so that proper pressures are attained in the tubesor bypasses 28 and 32 respectively, whereby suitable quantities of oxygen and nitrous oxide are forced through the orifices 61. and. 62

respectively, so as to attain that predetermined.

mixture of the gases.

oxide may be supplied both to the patientand to the resilientreservoir 49,by positioning the pointer 94 of the handle 89, in register withthecentral boss 93, this being the position of the. valve and handle shown upon Figs. 2, 3, and 5. As ex plained hereinabove, theinherent tendency of the reservoir 49 tov collapse, maintains a suitable pressure upon the gas supplied to the patient, in

spite of the fact that the patient withdraws the gas therefrom in an intermittent flow as determined by the rapidity of his respiration. As will be well understood, supplying the mixture of oxygen and nitrous oxide to the patient inthis Preferably a coil manner, will effect anaesthesia. Should it eventution, the face mask becomes disturbed or the patient is permitted to breathe a quantity of air which causes his partial resuscitation, the operator or the anaasthetist will beable to detect such .change in'the patients condition; and by throwing-.the-handle 89 of the valve toward that side of the apparatus with which the cylinders 23 containing nitrous oxide are associated, he may cause pure N20 to be suppliedto the patient. As will be readily appreciated, this adjustment of the apparatus may be effected almost instantaneously, whereby any change in the profundity of the patients anaesthesia, may quickly be compensated for.

Similarly, should itdevelop that the patient starts to go too deeplyunder the influence of the anesthetic, he may be promptly revived either partially or completely, according to the will of the operator, by throwing the handle 89 in the oppositedirection, whereupon pure oxygen may be supplied to the patient, in an increased quantity.

An important feature of the apparatus of the present invention, lies in the fact that whenever the'valve'36 is moved from one position to am other, the reservoir 49, 69, or 82, as the case may be,-from communication with which thevalve is moved, is sealedofi" tightly, with the result that a suitable quantity of gas is retained therein at lung pressure, so that it is available for subsequent instant use when occasion therefor arises. Consequently, whenever the valve 36 is moved to establish communication between the patient and any one of the reservoirs 49; 69, or 82, the selected gas or mixture of gases starts to flow to the patient instantaneously, and at lung pressure, so that the effect upon the patient of; the alteration of the composition of the gas supplied to him, is practically instantaneous.

. Thus it may be seen that the patients condivery small adjustmentof the richness of the anwsthetic gas will compensate therefor, the operator may easily and promptly take care of the situation. by'throwing the handle 89 to the proper side so as to eflect'admissionof pure oxygen or pure N20 according to thecircumstances, and then immediately throwing handle 89 back to intermediate position. Inasmuch as both oxygen and nitrous oxide are held in readiness for immediate withdrawal, a suflicient quantity of the selected gas-will be supplied to the patient, to efiect-a material alteration of the depth of his v V anaesthesia, even though communication is estab- This mixture of gases of oxygen and nitrous lished between the patient and the reservoirs 69 or 82, containing the selected gas, for only a very short space or time.

It is to be understood that the details of the invention as herein disclosed, are subject to alteration within the spirit or scope of the appended claims.

I claim:

1. In an amesthetizing apparatus, a source of supply of a nutrient gas, a source of supply of an leading from each of said sources of supply to said valve chamber, a resiliently distensible reservoir adapted to be connected to each of said supply tubes, both of said reservoirs communicating-separately with said valve chamber at points equally spaced from the entrances of their respective supply tubes into said valve chamber, and said inlet ports being separated a distance on said valve corresponding to the spacing between respective points of entry of a reservoir and its respective supply tube into said chamber whereby the valve may be moved to establish communication optionally between said outlet port and either inlet port and its respective reservoir.

2. In an anaesthetizing apparatus, a source of supply of a nutrient gas, a source of supply of an anaesthetic gas, a valve chamber, a valve movable therein having oppositely disposed inlet ports and an outlet port, all of said ports being in communication with each other, a delivery tube leading from said valve chamber and communicating with said outlet port, a supply tube leading from each of said sources of supply into said valve chamber, a resiliently distensible reservoir adapted to be connected to each of said supply tubes by said valve'chamber at a point'opposite that at which its respective supply tube enters said valve chamber, a third resiliently distensible reservoir communicating with said chamber, and bypasses from both of said supply tubes entering said valve chamber at a common location opposite that at which said third reservoir communicates therewith.

3. In an aneesthetizing apparatus, a source of supply of a nutrient gas, a source of supply of an anesthetic gas, a valve chamber, a valve movable therein having oppositely disposed inlet ports and an outlet port, all of said ports being in communication with each other, a delivery tube leading from said valve chamber and communicating with said outlet port, a supply tube leading from each of said sources of supply into said valve chamber, a pair of resiliently distensible reservoirs adapted to-be connected to each of said supply tubes by said valve chamber at a point opposite that at which its respective supply tube enters the valve chamber, a third resiliently distensible reservoir communicating with said valve chamber at a point situated between the entrances of said supply tubes thereinto, and bypasses from both of said supply tubes entering said valve chamber at a common location opposite that at whichsaid third reservoir communicates therewith.

4. In an anmsthetizing apparatus, a source of supply of a nutrient gas, a source of supply of an anaesthetic gas, a valve chamber, a valve move able therein having oppositely disposed inlet ports and an outlet port, all of said ports being in communication with each other, a delivery tube leading from said' valve chamber and communicating with said outlet port, a supply tube which its respective supply tube enters the valve chamber, a third resiliently distensible reservoir communicating with said valve chamber, bypasses from both of said supply tubes entering said valve chamber at a common location opposite that at which said third reservoir communicates therewith, means for predetermining the rate of flow through each of said bypasses, and means for varying the rate of flow through the supply tube forsaid nutrient gas without affecting the rate of flow through the bypasses connected therewith. v

5. An anaesthetizing apparatus comprising a source of supply of oxygen, a source of supply of nitrous oxide, a valve chamber, a supply tube each for said sources of supply and leading to the valve chamber, each supply tube having a 7 passes, or establishing a communication between the valve chamber and both the bypasses and the mixed gas reservoir while closing communication between the valve chamber and both the supply tubes'and both straight gas reservoirs, and a delivery tube leading from the valve chamber.

6. An anaesthetizing apparatus comprising a source of supply of oxygen, a source of supply of nitrous oxide, a valve chamber, a supply tube each for said sources of supply and leading to the valve chamber, each supply tube having a bypass leading to the valve chamber, three resiliently distensible reservoirs, the first for oxygen, the second for nitrous oxide, and the third for a mixture of said two gases, each reservoir having a conduit leading to the valve chamber, a rotatable valve member located within the valve chamber and having ports so spaced that communication may be established optionally between the valve chamber and one of said straight gas reservoirs and its respective supply tube while closing communication with the other supply tube, the other two reservoirs, and the bypasses, or establishing communication between the valve chamber and both bypasses and the third reservoir while closing communication with the first and second reservoirs and both supply tubes, and a delivery tube leading fromthe valve chamber.

ORIN HARRY PEAK. V 

